Evolutionary wireless communication systems should be able to support legacy system equipment. The IEEE 802.16(m) protocol is an evolution of the WiMax OFDMA specification for IEEE 802.16(e) protocol. Thus, some 802.16(e) equipment, e.g. base stations and mobile stations, will coexist with 802.16(m) equipment as equipment for the 802.16(m) protocol is being deployed and used. As the base stations and mobile stations for these different protocols are being used together, the frame structures for the newer advanced protocol need to support the frame structure for the legacy protocols.
The legacy 802.16(e) protocol includes two modes for subchannelization, or allocating physical resources for transmission. One mode is Partial Usage of Subchannels (PUSC). In the UL 802.16(e) protocol, the minimum resource allocation unit for PUSC is 4 contiguous subcarriers by 3 OFDM symbols. This minimum unit is commonly known as a tile. One resource allocation may contain multiple tiles that are spread across the whole frequency band. Another mode of subchannelization is Band Adaptive Modulation and Coding (Band-AMC). The minimum resource allocation unit of Band-AMC is a bin, or 9 contiguous subcarriers by 1 OFDM symbol. One resource allocation in Band-AMC may contain multiple bins and across 3 contiguous OFDM symbols. In the legacy 802.16(e) protocol, control channel can only be transmitted using PUSC mode, while data channels can be transmitted using either PUSC or Band-AMC mode. As proposed for 802.16 (m), the minimum building block consists of 6 or 9, or multiples of 6 or 9 contiguous subcarriers.
The need to support legacy 802.16(e) systems in 802.16(m) can lead to complex system design. As noted above, the tile size of PUSC mode of the 802.16(e) and 802.16(m) are not identical and are not multiples of one another. If both tile sizes are supported for 802.16(m) data channels, it can lead to increased complexity for 802.16(m) mobile stations. What is needed therefore is a frame structure and method that will support the legacy 802.16(e) protocol in 802.16(m) without increasing the complexity of 802.16(m) system.
The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description with the accompanying drawings. The drawings may have been simplified for clarity and are not drawn to scale.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.